Cat & Dog Health • Cardiology

Heart problems in cats and dogs: what signs should owners watch for?

Heart disease may remain silent for a long time. When signs appear, they can include breathing changes, exercise intolerance, coughing in some dogs, fainting, weakness, or fluid accumulation.

Veterinarian reviewedUpdated Aug 20, 2026
The key takeaway

Difficulty breathing at rest is an emergency. Cats with heart disease may not cough, so increased resting respiratory rate or labored breathing can be especially important.

Emergency: open-mouth breathing in a cat, blue/gray gums, severe respiratory effort, collapse, or sudden painful hind-limb weakness requires immediate veterinary care.

Common signs in dogs

Reduced stamina, coughing, rapid breathing at rest, fainting, abdominal enlargement, weakness, or weight loss may occur depending on the disease. Coughing has many non-cardiac causes, so it should not be used alone to diagnose heart failure.

Common signs in cats

Cats often hide cardiac disease. Rapid or labored breathing, reduced activity, poor appetite, or sudden hind-limb weakness from an arterial clot can be presenting signs. A heart murmur may be detected during routine examination, but some cats with significant disease have no obvious murmur.

How is heart disease evaluated?

Depending on the findings, testing may include chest radiographs, echocardiography, ECG, blood pressure, cardiac biomarkers, or blood tests for other diseases. The best combination depends on species, age, symptoms, and suspected condition.

Monitoring at home

For pets with known heart disease, your veterinarian may ask you to count sleeping or resting respiratory rate. Changes from the individual pet’s baseline can be more useful than a single isolated number. Do not start or change cardiac medication without veterinary direction.